Plasma enhanced method for increasing silicon-containing photoresist selectivity

Abstract

Provided is a method for increasing an etching selectivity of photoresist material. The method initiates with providing a substrate with a developed photoresist layer. The developed photoresist layer on the substrate is formulated to contain a hardening agent. Next, the substrate is exposed to a gas, where the gas is formulated to interact with the hardening agent. A portion of the developed photoresist layer is then converted to a hardened layer where the hardened layer is created by an interaction of the hardening agent with the gas. Some notable advantages of the discussed methods of increasing the selectivity of a photoresist include improved etch profile control. Additionally, by combining fabrication steps such as the hardening of the photoresist in an etch chamber, downstream etching processes may be performed without having to transfer the wafer to an additional chamber, thereby improving wafer throughput while minimizing handling.

What is claimed is:  
     
       1. An apparatus for curing a photoresist, comprising: 
       a chamber, the chamber having at least one gas inlet, the gas inlet being adapted to introduce a gas into the chamber;  
       a support within the chamber; and  
       a substrate on the support, the substrate having a developed silicon containing photoresist disposed over a non-silicon containing photoresist layer, the developed silicon containing photoresist layer interacting with the gas to form a hardened layer at a top portion of the developed silicon containing photoresist layer, wherein the non-silicon containing photoresist layer is partially exposed when the silicon containing layer is developed.  
     
     
       2. The apparatus as recited in  claim 1 , wherein the gas is one of oxygen and ammonia. 
     
     
       3. The apparatus as recited in  claim 1 , wherein the support is a chuck. 
     
     
       4. The apparatus as recited in  claim 1 , wherein the non-silicon containing photoresist layer is about 6000 Å thick and the non-silicon containing photoresist layer covers an entire surface over which the non-silicon containing photoresist layer is disposed. 
     
     
       5. The apparatus as recited in  claim 1 , wherein an etch selectivity ratio of the developed silicon containing photoresist layer and the non-silicon containing photoresist layer is between about 8 and about 15. 
     
     
       6. The apparatus as recited in  claim 1 , wherein the hardened layer includes one of silicon dioxide and silicon nitride. 
     
     
       7. The apparatus as recited in  claim 1 , wherein the chamber is capable of developing the developed silicon containing photoresist layer and performing a subsequent etch operation on the substrate. 
     
     
       8. A substrate having enhanced photoresist selectivity for an etch operation, comprising: 
       an interlayer dielectric (ILD) layer;  
       a non-silicon containing photoresist layer disposed over the ILD layer; and  
       a developed silicon containing photoresist layer disposed over the non-silicon containing photoresist layer, the developed silicone layer having openings defined therein partially exposing a top surface pf the non-silicon containing photoresist layer.  
     
     
       9. The substrate of  claim 8 , wherein a top portion of the developed silicon containing photoresist layer is hardened through interaction of silicon with one of ammonia gas and oxygen gas. 
     
     
       10. The substrate of  claim 9 , wherein the top portion is between about 5% and about 75% of the developed silicon containing photoresist layer. 
     
     
       11. The substrate of  claim 9 , wherein the top portion of the developed silicon containing photoresist layer is silicon nitride. 
     
     
       12. The substrate of  claim 8 , wherein the non-silicon containing photoresist layer has a thickness of about 6000 Å.